One man has been arrested amid bursts of gunfire as police stormed towards a house in Southwark following terrorist incidents in London Bridge and Borough Market in the UK capital.

Up to seven people are feared dead while around 20 were injured in the attacks that started when a van rammed into people on London Bridge.

Men armed with knives are then thought to have stabbed other victims while a suspect was pictured lying on the ground with canisters strapped to his chest.

A suspect with canisters wrapped around him is seen lying on the ground after the terror attack on London Bridge (Image: Gabriele Sciotto/AFP/Getty)

Alex Shellum was in The Mudlark pub, close to London Bridge, at around 10pm when a woman in her early 20s "staggered into the pub".

"She was bleeding heavily from the neck and from her mouth," he told BBC News.

"It appeared to myself and to my friends that her throat had been cut. People went to her aid."

He said the pub was then closed and armed police told them to leave the area.

He said: "I could see on my left a further individual was having CPR performed on them by the emergency services."

Officers tell people to get down inside pub near London Bridge

There have also been reports of knife-wielding assailants targeting a restaurant near London Bridge.

An eyewitness also saw an "Asian man in his mid thirties" with his hands tied behind his back as up to 30 police frogmarched him down the street, shouting at people to get away.

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Eyewitness John Bennet said: "As I was walking up the Borough High Street the police were crowded round a house on the right hand side.

"They had shields and were wearing masks and were running across the street shouting at one another.

"I heard what sounded like short bursts of gunfire. Suddenly they started shouting at us 'run away' ' get back' and people really were running for their lives.

"About 15 of us were running down Borough High street toward London Bridge followed by 30 armed police.

"They were spread put across the street.

"They had a man. There were four police either side of him and others crowded round. They had his hands tied behind his back.

"He was an Asian man, about five foot six, dark hair, mid thirties with stubble, wearing a dark jacket. He was being frogmarched quickly down the street.

"They crowded round him at the first corner then we were all ushered away as they extended the cordon.

"It was really scary. The police were round on a corner on the street, they had shields and guns.

"Then everyone started running, they had arrested a guy and were running with him."

Scotland Yard confirm there was also a stabbing in Vauxhall which is not connected.

A hunt is underway for other suspects.

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The incident started just after 10pm when three men were seen jumping out a white van on London Bridge after the vehicle had mowed people down.

The white van is said to have veered off the road and struck "15 or 20" people.

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Reports of stabbings and gunfire then emerged with one witness reporting that she saw three people whose throats were cut.

Another witness claimed they saw a person thrown "about 20ft in the air" by the vehicle.

(Image: Reuters)

He added: "Within my line of sight there must have been about five or six people on the ground. They looked either dead or dying."

Armed police in the area warned people to "run, hide and tell."

London Ambulance Service assistant director of operations Peter Rhodes said: "We have sent a number of ambulance crews, advanced paramedics and specialist response teams to the scene, with the first of our medics arriving in six minutes.

"An advanced trauma team from London's Air Ambulance has also been dispatched by car."

(Image: Sky News)

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Nick Archer, who was in the London Bridge area, said: "We came out of a bar on to the road and looked to my left and there was a guy, I thought he was just drinking but he was lying on the floor.

"And then a couple of seconds later, about three police vans flew past.

"He looked in a bad way."

Holly Jones, a BBC reporter at the bridge when the incident happened, said a van had swerved off the road into a crowd of pedestrians.

(Image: Sky News)

"A white van driver came speeding - probably about 50mph - veered of the road into the crowds of people who were walking along the pavement," she told BBC News.

"He swerved right round me and then hit about five or six people. He hit about two people in front of me and then three behind.

"I'd say there are about four severely injured people. They all have paramedics assisting them at the moment."

(Image: Sky News)

It comes just two months after terrorist Khalid Masood mowed down pedestrians on the city's Westminster Bridge before stabbing an unarmed policeman in a deadly rampage.